Antibactericidal Effect Research Articles

Antimicrobial characteristics of endophytic Aspergillus terreus and acute oral toxicity analysis

BackgroundEndophytic fungi produce biologically robust metabolites suitable for diverse applications, which support the increasing exploration of these fungi. The study aimed to investigate the in vitro antimicrobial properties of the metabolites of endophytic fungus Aspergillus terreus which isolated from the leaves of Psidium guajava plants while the acute oral toxicity was assessed in vivo. ResultsA. terreus (OR125572) was successfully isolated for the first time from P. guajava. The ethyl acetate extract of A. terreus exhibited antibactericidal effects against Enterobacter aerogenes with a minimum inhibitory concentration of 18.75 mg/ml in contrast to 75.00 ± 0.0, 37.50, and 37.50 mg/ml, respectively against Staphylococcus aureus, Escherichia coli, and Bacillus sphaericus were 75.00 ± 0.0, 37.50, and 37.50 mg/ml, respectively. Analysis of the crude extract obtained from A. terreus by GC-MS revealed a total of 32 distinct compounds. The major components included 1,2-benzenedicarboxylic acid, di-iso-octyl ester; hexyl oxecan-2-one and phenol. The acute oral toxicity study found no symptoms of toxicity and no mortality until the 14th d, suggesting that the LD50 value of A. terreus extract might exceed 1 ml/kg. The group receiving 0.5 ml/kg of A. terreus extract experienced a 42.9% increase in body weight, while administration of varying dosages resulted in a significant reduction in MCV levels. There was also a significant increase in the proportion of monocytes across all treated groups. ConclusionsThe study demonstrated the potential of A. terreus as a source of antimicrobial and other bioactive compounds, with relatively low acute toxicity.How to cite: Shehabeldine AM, Abdelaziz AM, Abdel-Maksoud MA, et al. Antimicrobial characteristics of endophytic Aspergillus terreus and acute oral toxicity analysis. Electron J Biotechnol 2024;72. https://doi.org/10.1016/j.ejbt.2024.07.003.

Intravaginal Delivery of Herbal Pharmaceutical Interventions for Uncomplicated UTIs in Women

Background: Urinary tract infection (UTIs) is the most common infection in women affecting approximately 75% of women worldwide during their pregnancy, and in pre and postmenopausal women. Typical symptoms include urinary frequency, urgency, suprapubic discomfort, and dysuria. Method: An introduction to the epidemiology of UTIs and detailed herbal nanoformulation treatment approach through novel intravaginal route is intended through this narrative review. UTIs are associated with significant morbidity and mortality, and they affect the quality of life of the affected patients. Multidrug-resistant bacteria and recurrent UTIs are becoming more common. Development of resistance, adverse effects of antibiotics, and other associated problems lead to establishing the research framework to find out the alternative approaches in controlling UTIs. Antibiotic- free treatments for uncomplicated urinary tract infections UTIs should be used, saving drugs for severe infections. Herbal medication might be used instead of antibiotics for uncomplicated UTIs, in addition to analgesics for purely symptomatic treatment. Conclusion: This review identifies the pathophysiology of UTI, distinguish the intravaginal route as an alternative to oral delivery route, summarizes the management of urinary tract infections and highlights the anti-uropathogenic and anti-bactericidal effects of herbal approaches to prevent or treat urinary tract infections.

Quantitative generation of ROS and their effective photocatalytic antibacterial activity of high-intensity universal P25 network films: The role of ROS

Reactive oxygen species (ROS) generation and utilization were the foundation for the photocatalytic degradation of pollutants or anti-bactericidal effect. Especially for solid-phase film photocatalysis, a simple and firm immobilization method that ensured exposure of active sites and effective production of ROS was the key. Presently, a P25 network films was achieved using water-based polyurethane acrylate (WPUA) as adhesive through a simple and convenient direct spraying method. The physical and chemical properties of the P25 network films were characterized and the results showed that P25 was firmly adhered on the metal wire mesh and fully exposed the active sites of P25. Dynamic generation of ROS on 304SS@P25 films interface was systematically investigated. The concentration of hydroxyl radicals (•OH), superoxide radicals (O2•−) and hydrogen peroxide (H2O2) on 10 cm × 3 cm 304SS@P25 after 2 h of UV irradiation were 9.4 ± 0.3 × 10−9 M, 7.6 ± 0.3 × 10−9 M, and 11.7 ± 0.9 × 10−6 M, respectively, which was similar with ROS generation of P25 nanoparticle suspensions. In addition, the ROS-mediated antibacterial effect of 304SS@P25 films was investigated, and a linear correlation was found between the concentration of ROS generated and the E. coli sterilization rate. Furthermore, 304SS@P25 films could be successfully applied in the air sterilizer to exhibit a good bactericidal effect. This ROS-oriented photocatalyst immobilization method opened up a new pathway for water and air purification and provided a new strategy in the field of photocatalytic antibacterial technology.

Application of Acidulants to Control Salmonella spp. in Rendered Animal Fats and Oils with Different Levels of Unsaturation.

Salmonella-contaminated pet foods could potentially become a source of human salmonellosis. This study evaluated the survival of Salmonella without and with the addition of acidulants in different fat types (chicken fat (CF), canola oil (CO), Menhaden fish oil (FO), lard (La), and tallow (Ta)) commonly used to coat dry pet food kibbles. The minimum inhibitory concentration (MIC) of individual acidulants and the combination were determined using the broth microdilution method. Autoclave-sterilized rendered fats were treated with pre-determined concentrations of antimicrobial acidulants (0.5% sodium bisulfate (SBS), 0.5% phosphoric acid (PA), 0.25% lactic acid (LA), etc.) and incubated overnight at 45 °C. The treated fats were inoculated with approximately eight logs of a Salmonella cocktail. Microbiological analyses were conducted separately for the fat-phase and water-phase at predetermined time intervals (0, 2, 6, 12, and 24 h) by plating them onto TSA plates. After incubating at 37 °C for 24 h, the plate count results were expressed as log CFU/mL. The MIC of SBS was 0.3125%, and of PA and LA were both 0.1953% against cocktail Salmonella serotypes. We observed a possible synergistic effect when SBS and organic acid were combined. All the acidulant tested at targeted concentrations individually as well as in combination with organic acids were highly effective against Salmonella spp. (non-detectable within 2 h) across different fat types. A potent anti-bactericidal effect leading to non-detectable Salmonella immediately (<1 h) at 45 °C was observed in the aqueous phase of the fish oil system, even without the addition of acidulants. These findings are significant for the dry pet food industries, where potential post-processing contamination of Salmonella could be controlled by treating fats and oils with acidulants.

Effect of Gentamicin Collagen Sponge on Wound Healing: In Vivo Study and Assessment of Its Effectiveness against Nosocomial Bacteria

Background: Gentamicin collagen sponge (Genta-Coll) reportedly has a hemostatic effect and promotes wound healing. However, it may also interfere with wound healing by causing foreign body reactions. We planned to analyze the effect of Genta-Coll on wound healing by inducing muscle defects in the rectus abdominis muscle of rats. We also assessed the effectiveness of Genta-Coll in preventing surgical site infections (SSIs) using the zone of inhibition tests to determine the sensitivity of pathogenic bacteria.Methods: We created an 8×8-mm muscle defect in both recti abdominis of 15 white Sprague-Dawley rats and distributed them into the control group (no care) and group A (Genta-Coll). Three biopsies were performed for histologic analysis (on days 3, 7, and 27). In the second study, we placed Genta-Coll on Mueller–Hinton agar plates seeded with pathogenic microorganisms commonly responsible for SSIs. The zone of inhibition was measured after 24 and 48 hours of incubation.Results: Group A showed a slightly higher score for foreign body giant cells and inflammation, with no significant difference. Granulation and neovascularization were constantly high in group A, and muscle regeneration was also high in group A. Extracellular matrix formation advanced at a similar pace in both groups. Genta-Coll created a zone of inhibition against all microorganisms except for Candida albicans. The effect lasted without change between 24 and 48 hours.Conclusion: While foreign body reactions and inflammation increased in group A, wound healing was unaffected. Genta-Coll can promote faster wound healing with an anti-bactericidal effect against SSI pathogens.

Characterization and Toxicity of Hypoxoside Capped Silver Nanoparticles.

The reducing potential of plant extracts in the green synthesis of nanoparticles has been associated with their phytochemicals. Although pharmacologically inactive, a norlignan diglucoside “hypoxoside” (HP) occurs in large quantities in the extract of Hypoxis hemerocallidea (HE). In this work, HP was isolated from HE where both were used in the biosynthesis of the corresponding silver nanoparticles (HP-AgNPs and HE-AgNPs). The AgNPs were fully characterized using various physicochemical techniques and their antimicrobial and anticancer properties were evaluated. Transmission electron microscopy (TEM) revealed sizes of 24.3 ± 4 nm for the HE-AgNPs and 3.9 ± 1.6 nm for the HP-AgNPs. The HE-AgNPs demonstrated enhanced anti-bactericidal effects on Escherichia coli and Salmonella enterica with a minimum inhibitory concentration (MIC) value of 1.95 µg/mL, competing well with the standard drug. The cytotoxic activity showed that the HE-AgNPs reduced cell viability with an IC50 of 0.81 and 4.0 µg/mL, respectively, for the U87 and U251 cells, while the HP-AgNPs displayed 0.20 and 0.55 µg/mL for both cell lines, respectively. Furthermore, while the HE-AgNPs were selective to U87 alone, the HP-AgNPs were selective to both glioblastoma cells tested. The study demonstrated the ability of a single phytoconstituent (hypoxoside), not only as the chief bioreductant in the extract, but also as a standalone reducing and capping agent, producing ultra-small, spherical, and monodispersed AgNPs with enhanced biological properties.

A bimetallic load-bearing bioceramics of TiO2 @ ZrO2 integrated polycaprolactone fibrous tissue construct exhibits anti bactericidal effect and induces osteogenesis in MC3T3-E1 cells

Bioactive mesoporous binary metal oxide nanoparticles allied with polymeric scaffolds can mimic natural extracellular matrix because of their self-mineralized functional matrix. Herein, we developed fibrous scaffolds of polycaprolactone (PCL) integrating well-dispersed TiO2@ZrO2 nanoparticles (NPs) via electrospinning for a tissue engineering approach. The scaffold with 0.1 wt% of bioceramic (TiO2@ZrO2) shows synergistic effects on physicochemical and bioactivity suited to stem cell attachment/proliferation. The bioceramics-based scaffold shows excellent antibacterial activity that can prevent implant-associated infections. In addition, the TiO2@ZrO2 in scaffold serves as a stem cell microenvironment to accelerate cell-to-cell interactions, including cell growth, morphology/orientation, differentiation, and regeneration. The NPs in PCL exert superior biocompatibility on MC3T3-E1 cells inducing osteogenic differentiation. The ALP activity and ARS staining confirm the upregulation of bone-related proteins and minerals suggesting the scaffolds exhibit osteoinductive abilities and contribute to bone cell regeneration. Based on this result, the bimetallic oxide could become a novel bone ceramic tailor TiO2@ZrO2 composite tissue-construct and keep potential nanomaterials-based scaffold for bone tissue engineering strategy.

Optimum dietary processed sulfur (Immuno-F) level has antibiotic effects on the growth, hematology and disease resistance of juvenile olive flounder, Paralichthys olivaceus

A great deal of research has been focused on feed additives that can boost the immune system of cultured fish since the food and drug administration (FDA) banned the use of antibiotics as feed supplementations in 2017. Sulfur is generally an essential element for the growth of animals, and sulfur-containing compounds are known to have anti-oxidant and anti-bactericidal effects. Although dietary sulfur has many potentials as a functional additive as well as an antibiotic replacer, it can also be toxic when supplemented at the high levels. Thus, it is necessary to determine the optimum amount in fish diet to exert positive effects on immune responses. Hence, an 8-week feeding trial was conducted to evaluate the optimum dietary processed sulfur (Immuno-F) level to replace antibiotic oxytetracycline (OTC) in juvenile olive flounder based on growth performance, hematology, and disease resistance. Each of 20 fish averaging 12.6 ± 0.17 g (mean ± SD) were randomly allocated into 8 groups of three tanks, and fed one of the eight isonitrogenous and isocaloric (crude protein 46.7 %, 160 kJ g−1) experimental diets formulated by supplementing Immuno-F at 0 ppm (Cont), 25 ppm (F25), 50 ppm (F50), 250 ppm (F250), 500 ppm (F500), 1000 ppm (F1000) and 2000 ppm (F2000), or oxytetracycline 4000 ppm (OTC4000). Weight gain and specific growth rate of fish fed F25, F500, and OTC4000 diets were significantly higher than those of fish fed F1000 and F2000 diets. In addition, superoxide dismutase, lysozyme and myeloperoxidase activities were not significantly different between sulfur and OTC supplemented groups. However, serum triglyceride levels of fish fed F1000 diet were significantly higher than those of fish fed F25, F50, F250, F500 and OTC4000 diets. In challenge test against Edwardsiella tarda at the 6th day, cumulative survival rates of fish fed F50 diet were slightly higher than those of fish fed F250-F2000 diets. Therefore, these results indicate that dietary processed sulfur at 50 ppm supplementation could replace antibiotic (OTC) in juvenile olive flounder.

Prussian blue and collagen loaded chitosan nanofibers with NIR-controlled NO release and photothermal activities for wound healing

1 Prussian blue and collagen loaded chitosan electrospun nanofibers were fabricated. 2 The chitosan nanofibers possess NIR controlled NO release and PTT activities. 3 The nanofibers displayed synergetic antibacterial against E. coli and S. aureus . 4 The nanofibers promoted collagen deposition, cell growth, and epithelialization. 5 The nanofibers provide sufficient biosafety for wound healing. Nitric oxide (NO) has emerged as a potential wound therapeutic agent due to its pivotal role in the wound healing processes. Nevertheless, NO-based therapy for clinical applications is still restricted due to its gaseous state and short half-life. Here we exploited a wound dressing by incorporating sodium nitroprusside doped prussian blue nanoparticals and Type I collagen into the chitosan/poly(vinyl alcohol) nanofibers through the electrospinning method. This hybrid nanofibrous scaffold possess the excellent abilities of NIR controlled NO release, photothermal therapy, and imitation of extra-cellular matrix-like architecture. These synergistic effects could enhance their anti-bactericidal effects in vitro and furthermore accelerate wound healing in vivo when compared to control groups. Histological analysis demonstrated the scaffold could promote fibroblast growth and accelerate epithelialization. Moreover, no apparent histological toxicology and negligible damage to major organs were observed, which provided sufficient biosafety for in vivo application. These data indicate the fabricated hybrid nanofibrous scaffold could be used as an ideal candidate for accelerating wound healing and treating chronic wounds.

Design, synthesis, and antibacterial evaluation of PFK-158 derivatives as potent agents against drug-resistant bacteria

Infections caused by antibiotic resistant bacteria are a major health concern throughout the world. It is well known that PFK-158 can enhance the antibacterial effect of polymyxin, but its own anti-bactericidal effect is rarely discussed. In order to investigate the anti-bactericidal effect of PFK-158 and its derivatives, PFK-158 and 35 derivatives were designed, synthesized, and evaluated for their antibacterial activities. Compounds A1, A3, A14, A15 and B6 exhibited potent antibacterial effect against both clinical drug sensitive and resistant Gram-positive bacteria, and they are 2–8 folds more potent than levofloxacin against Methicillin-resistant staphylococcus epidermidis (MRSE). A significant synergistic effect of these compounds and polymyxin against drug-resistant Gram-negative bacteria, which is similar to PFK-158 was also observed. The result can provided a new and broader prospect for the development of new medicine against drug-resistant bacteria.

Fragmentation Study, Dual Anti-Bactericidal and Anti-Viral Effects and Molecular Docking of Cobalt(III) Complexes.

Considering our previous findings on the remarkable activity exhibited by cobalt(III) with 2-acetylpyridine-N(4)-R-thiosemicarbazone (Hatc-R) compounds against Mycobacterium tuberculosis, the present study aimed to explored new structure features of the complexes of the type [Co(atc--R)2]Cl, where R = methyl (Me, 1) or phenyl (Ph, 2) (13C NMR, high-resolution mass spectrometry, LC–MS/MS, fragmentation study) together with its antibacterial and antiviral biological activities. The minimal inhibitory and minimal bactericidal concentrations (MIC and MBC) were determined, as well as the antiviral potential of the complexes on chikungunya virus (CHIKV) infection in vitro and cell viability. [Co(atc-Ph)2]Cl revealed promising MIC and MBC values which ranged from 0.39 to 0.78 µg/mL in two strains tested and presented high potential against CHIKV by reducing viral replication by up to 80%. The results showed that the biological activity is strongly influenced by the peripheral substituent groups at the N(4) position of the atc-R1− ligands. In addition, molecular docking analysis was performed. The relative binding energy of the docked compound with five bacteria strains was found in the range of −3.45 and −9.55 kcal/mol. Thus, this work highlights the good potential of cobalt(III) complexes and provide support for future studies on this molecule aiming at its antibacterial and antiviral therapeutic application.

Synthesis, characterization, toxic substructure prediction, hepatotoxicity evaluation, marine pathogenic bacteria inhibition, and DFT calculations of a new hydrazone derived from isoniazid

A new hydrazide-hydrazone; N‵-[(3Z)-6-bromo-2-oxo-2,3-dihydro-1H-indol-3-ylidene] pyridine-4-carbohydrazide (IH) has been prepared via condensation of the anti-tubercular drug isonicotinylhydrazide (INH) and 6-bromoindoline-2,3-dione. The newly synthesized compound has been characterized by different spectroscopic methods such as UV, IR, NMR (1H, 13C), and mass spectrometry. The antioxidant effect of IH was investigated by DPPH, superoxide anion, and hydrogen peroxide scavenging assays. Results indicated that IH exhibits an excellent hydrogen peroxide-scavenging effect with an IC50 of 4.46 ± 0.2 μg/mL, a good effect against superoxide anion with an IC50 of 125 ± 66 μg/mL, and a moderate effect towards DPPH with inhibition percentage of 54%. In addition, IH was subjected to a density functional theory (DFT) study, where lipophilicity, and toxic substructure (toxicophores) of IH were predicted. Our computational results indicate high chemical reactivity of IH in DMSO, and the lipophilic character with logP value of 1.78 at the physiological pH 7.4. Moreover, hepatotoxicity results showed non-toxic effect of IH to mice liver at the administrated dose of 400 mg/kg. IH was also investigated for its antibacterial effect against the marine pathogenic bacteria, Vibrio anguillarum and Photobacterium damselae. Results revealed an excellent antibactericidal effect of IH against Vibrio anguillarum with inhibition percentages of 97.90% and 98.87% at 500 μg/mL and 1000 μg/mL respectively. Additionally, IH exhibited a significant effect against Photobacterium damselae with inhibition percentages of 97.66% and 98.08% at the same concentrations, respectively.

Antibacterial activity and mechanism of action saponins from Chenopodium quinoa Willd. husks against foodborne pathogenic bacteria

The present study investigated the chemical composition of quinoa saponins and examined their possible antimicrobial modes of action against foodborne pathogenic bacteria.Six different compounds (Q1-Q6) were extracted from quinoa husks, separated/purified by column chromatography and identified by HPLC/MS and NMR. The anti-bactericidal effects against six types of bacteria, Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus, Salmonella enteritidis, Pseudomonas aeruginosa, and Listeria ivanovii, were determined by the disk diffusion method and assessment of the MIC/MBC. The changes in membrane integrity were tested using a microplate reader, a flow cytometer, and a transmission electron microscopy.All the compounds exerted anti-bactericidal effects against S. aureus, S. epidermidis and B. cereus. Q4 showed the strongest activity against S. aureus and S. epidermidis, with an MIC value of 0.0625 mg/mL and an MBC value of 0.125 mg/mL. The concentration of quinoa saponin Q4 exhibited a dose-dependent relationship with its anti-bactericidal effect. In fact, a dose-effect relationship was found between the concentration of all quinoa saponins and their bacteriostatic effects. In addition, the release of nucleic acids and proteins from B. cereus increased gradually with increases in the Q4 concentration, and the membrane structure of B. cereus was destroyed by Q4.Notably, quinoa saponins caused severe damage to the tested bacteria through degradation of the cell wall followed by disruption of the cytoplasmic membrane and membrane proteins, which resulted in leakage of the cell contents.

Plasmonic Ag3PO4/EG photoanode for visible light-driven photoelectrocatalytic degradation of diuretic drug

Abstract In this study, a novel photoanode was fabricated from silver orthophosphate (Ag3PO4) and exfoliated graphite (EG) and evaluated for the degradation of hydrochlorothiazide drug and antibactericidal effect. The composite materials were first characterized by using XRD, FTIR, Raman, TGA, FE-SEM, TEM, EDS, UV–Vis DRS, PL, XPS, and AFM to confirm their structural integrity. XRD, FE-SEM, TEM, and XPS revealed the presence of silver (Ag) nanoparticles formed upon the addition of methyl viologen (MV). The Ag/Ag3PO4(5% MV)/EG photoanode showed the highest efficient of 87.1% compared to EG (28.1%), Ag3PO4/EG (75.1%), Ag/Ag3PO4 (10% MV)/EG (61.3%), and Ag/Ag3PO4(20% MV)/EG anode (55.6%), respectively. ICP-OES indicated Ag leachability of 0.714 ppm after 180 min of the reaction process. The trapping experiments confirmed that h+ and OH were the most active species for the degradation of HCTZ. The intermediates were analyzed with HPLC and the degradation mechanism entailed ring opening via cleavage of C–N bond and desulfonation of the products. Moreover, the photodegradation pathway was hypothesized. The materials displayed appreciable antibacterial activity on Gram-negative Escherichia coli (E. coli). This work provided an attractive avenue to fabricate highly photoelectrocatalytic electrodes with appreciable antimicrobial activity, with potential application in wastewater treatment.

The anti-bactericidal effects of FBW 7 silence in macrophage

The anti-bactericidal effects of <i>FBW</i> 7 silence in macrophage

Sol–gel grown Fe-doped ZnO nanoparticles: antibacterial and structural behaviors

Bacterial resistance to antibiotic treatment is an attractive issue. The discovery of new antibiotics often does not respond to the rapidly increasing bacterial resistance and needs innovative approaches to combat bacterial infections. The NPs size-dependent strong anti-bactericidal effect of Zn1−x Fe x O is inspected. Iron (Fe)-doped zinc-oxide (ZnO) nanoparticles (NPs) with composition Zn1−x Fe x O, where x = 0.0, 0.01, 0.03, and 0.05 are synthesized by sol–gel method from nitrate precursors and gelatin at fixed calcination temperature of 650 °C maintained for 2 h. The effects of Fe contents on the antibacterial and structural features of these NPs are inspected. XRD patterns display the single-crystalline nature of samples that exist in hexagonal wurtzite phase. SEM images reveal the existence of nearly spherical-shaped single-crystalline NPs. The observed broadening in the X-ray peaks confirms the evolution of crystalline phases in Zn1−x Fe x O NPs. A quantitative analysis of the size-dependent strain effects is performed through Williamson–Hall and size–strain plot, and its impact of strain on peak broadening is demonstrated. The values of strain, stress, and energy density are calculated. The estimated NPs mean size from FESEM and size–strain plot (SSP) is found to be in close agreement. ZnO NPs in the presence of Fe show some inhibition toward E. coli bacterial growth. Fe acting as impurity in the ZnO nanostructure enhances the power oxidation of ZnO resulting in an augmentation of antimicrobial activity.

Antimicrobial activity of a novel peracetic acid disinfectants of Bioxy H on resistant pathogens

Purpose: The disinfection of the resistant pathogens in environment is critical in manipulation of infection control. The usually used disinfectant as chlorine may produce toxic by-products. The purpose of this study was to determine the antimicrobial activity of a novel PAA disinfectant (Bioxy H) on several resistant pathogens. It is a modified PAA, is less erosive damage and toxicity than traditional PAA but reserve the effective antibactericidal effect. Methods: We add the powder on sterile water to obtain the Bioxy H 5.0% (W/ V) solution. The resistant microorganisms were cultured twice and obtain the broth suspension of 0.5 McFarland. This was accomplished by performing a standard kill-time suspension test using a 2 minutes contact time. Negative and positive controls were performed. Results: The tested bacteria and Candida albicans were killed to zero in 2 minutes contact time.

Production of human lysozyme in biofilm reactor and optimization of growth parameters of Kluyveromyces lactis K7

Lysozyme (1,4-β-N-acetylmuramidase) is a lytic enzyme, which degrades the bacterial cell wall. Lysozyme has been of interest in medicine, cosmetics, and food industries because of its anti-bactericidal effect. Kluyveromyces lactis K7 is a genetically modified organism that expresses human lysozyme. There is a need to improve the human lysozyme production by K. lactis K7 to make the human lysozyme more affordable. Biofilm reactor provides high biomass by including a solid support, which microorganisms grow around and within. Therefore, the aim of this study was to produce the human lysozyme in biofilm reactor and optimize the growth conditions of K. lactis K7 for the human lysozyme production in biofilm reactor with plastic composite support (PCS). The PCS, which includes polypropylene, soybean hull, soybean flour, bovine albumin, and salts, was selected based on biofilm formation on PCS (CFU/g), human lysozyme production (U/ml), and absorption of lysozyme inside the support. To find the optimum combination of growth parameters, a three-factor Box-Behnken design of response surface method was used. The results suggested that the optimum conditions for biomass and lysozyme productions were different (27°C, pH 6, 1.33vvm for biomass production; 25°C, pH 4, no aeration for lysozyme production). Then, different pH and aeration shift strategies were tested to increase the biomass at the first step and then secrete the lysozyme after the shift. As a result, the lysozyme production amount (141U/ml) at 25°C without pH and aeration control was significantly higher than the lysozyme amount at evaluated pH and aeration shift conditions (p < 0.05).

N-acetylcysteine and vancomycin alone and in combination against staphylococci biofilm

INTRODUCTION: The ability of staphylococci to produce biofilm is an important virulence mechanism that allows bacteria both to adhere and to live on artificial surfaces and to resist to the host immune factors and antibiotics. Staphylococcal infections have become increasingly difficult to treat due their antibiotic resistance. Therefore, there is a continuous need for new and effective treatment alternatives against staphylococcal infections. The main goal of this study was to test N-acetylcysteine (NAC) and vancomycin alone and in combination against S. epidermidis and S. aureus biofilms. METHODS: Biofilms were treated with NAC at minimum inhibitory concentration (MIC) and 10 × MIC concentrations and vancomycin at MIC and peak serum concentrations. RESULTS: The use of NAC 10 × MIC alone showed a significant antibactericidal effect, promoting a 4-5 log10 CFU/ mL reduction in biofilm cells. The combination of NAC 10 × MIC with vancomycin (independently of the concentration used) reduced significantly the number of biofilm cells for all strains evaluated (5-6 log10). CONCLUSION: N-acetylcysteine associated to vancomycin can be a potential therapeutic strategy in the treatment of infections associated to biofilms of S. epidermidis or S. aureus.

In vitro antibactericidal effect of disinfectants against major pathogens and disinfecting efficacy of hand washing

In vitro antibactericidal effect of disinfectants against major pathogens and disinfecting efficacy of hand washing